This invention relates to vehicles, and more particularly to a lift type vehicle incorporating a boom assembly and to a counterweight arrangement for the chassis of a vehicle to which the boom assembly is mounted.
Extendible boom forklift vehicles generally include a frame carrying ground-engaging wheels, and a motor and cab are mounted to the frame. A pair of spaced uprights are mounted to the frame toward the rear of the chassis, and a boom is pivotably mounted to the spaced uprights. A counterweight is mounted between the uprights toward the rear end of the chassis, and is operable to prevent tipping of the vehicle when a load is lifted by the boom assembly forwardly of the chassis.
In the past, a counterweight for this type of vehicle has been in the form of a weighted member mounted to the rear of the uprights. The weight of the weighted member varies according to the desired lifting capacity of the vehicle. For example, a heavier counterweight is mounted to the rear of the chassis to increase the lifting capacity of the vehicle. In the prior art, however, it has not been possible to provide sufficient counterweight for high capacity machines by mounting a counterweight member to the rear of the chassis. In order to provide additional counterweight for high capacity machines, the rear tires of the vehicle are filled with a calcium chloride solution to provide additional counterweight. While this functions well to provide the desired amount of counterweight, use of calcium chloride to fill the tires has been found to be less than an optimal solution.
In addition, the uprights in prior art forklifts of this type have been in the form of reinforced plate-like members, which provide adequate strength and support for the boom assembly and its associated components but which contribute little to counterweighting of the machine.
It is an object of the present invention to provide an improved counterweight arrangement for a lift type vehicle such as an extendible boom forklift. It is another object of the invention to utilize the uprights, to which the boom assembly is mounted and which are located at the rear of the vehicle, to provide counterweighting for the vehicle. Yet another object of the invention is to provide a counterweight arrangement which avoids the need to fill the tires with calcium chloride or any other counterweighting material. Yet another object of the invention is to provide a simple and efficient arrangement for providing the desired amount of counterweight to such a vehicle without significantly increasing the cost of the vehicle.
One aspect of the invention contemplates an improvement in a lift type vehicle having a chassis, a ground-engaging wheel arrangement carried by the chassis, an upright arrangement located on one side of the wheel arrangement and a boom assembly pivotably mounted to the upright arrangement for lifting a load on a side of the wheel arrangement opposite the upright arrangement. In accordance with this aspect of the invention, a first counterweight is associated with the upright arrangement for providing the vehicle with a first lifting capacity. A counterweight compartment is carried by the chassis and located on the same side of the wheel arrangement as the upright arrangement. A second counterweight is adapted for placement in the counterweight compartment for providing the vehicle with a second lifting capacity greater than the first lifting capacity. A third counterweight, having a weight greater than that of the second counterweight, is adapted for placement in the counterweight compartment for providing the vehicle with a third lifting capacity greater than the second lifting capacity. The upright arrangement is preferably in the form of a pair of spaced uprights, and the boom assembly is pivotably mounted to and between the pair of spaced uprights. Each upright is preferably in the form of a pair of spaced plates, and the first counterweight is in the form of a weighted filler member located between the pair of spaced plates. The counterweight compartment is preferably located between the pair of spaced uprights, and a door is preferably mounted to one of the uprights for selectively enclosing the counterweight compartment. The third counterweight preferably includes the second counterweight and at least one additional weighted member secured to the second counterweight for providing a weight to the third counterweight greater than that of the second counterweight. A retainer arrangement is preferably provided for securing the second and third counterweights in position within the counterweight compartment. In a preferred form, the counterweight compartment includes a floor for supporting the second and third counterweights, and the retainer arrangement is in the form of a bolt engageable with the floor and with the second and third counterweights for securing the second and third counterweights to the floor of the counterweight compartment.
Another aspect of the invention involves a counterweight system for a lift type vehicle having a chassis, a ground-engaging wheel arrangement carried by the chassis, and a lift mechanism mounted to the chassis. In accordance with this aspect of the invention, a counterweight compartment is carried by the chassis and located on a side of the wheel arrangement opposite the lift mechanism. The counterweight compartment is configured to receive two or more counterweights having different weights. A first one of the counterweights provides a first lifting capacity for the vehicle, and a second one of the counterweights provides a second lifting capacity different than the first lifting capacity. The lift mechanism is preferably in the form of an extendible boom assembly which is mounted to the chassis via a pair of uprights carried by the chassis on one side of the wheel arrangement, and extends to an opposite side of the wheel arrangement for lifting a load. The counterweight compartment is located on the same side of the wheel arrangement as the uprights, and is preferably disposed between the uprights. A second compartment may be located between the pair of uprights adjacent the counterweight compartment for housing certain components of the vehicle, and a door selectively encloses both the counterweight compartment and the second compartment. As summarized previously, the first counterweight is in the form of a first weighted member adapted to be received within the counterweight compartment, and the second counterweight is in the form of the first weighted member together with at least one additional weighted member adapted to be received within the counterweight compartment along with the first weighted member.
Another aspect of the invention contemplates a method of providing a lift type vehicle with a desired lifting capacity. The vehicle includes the same general components as summarized above, and the method involves providing the chassis with a counterweight-receiving area on the same side of the wheel arrangement as the upright arrangement, and providing first and second counterweights, with the second counterweight having a weight greater than that of the first counterweight. The method further involves positioning either the first or the second counterweight in the counterweight receiving area. Positioning the first counterweight in the counterweight receiving area provides the vehicle with a first lifting capacity, and positioning the second counterweight in the counterweight receiving area provides the vehicle with a second lifting capacity greater than the first lifting capacity. The counterweight receiving area is preferably in the form of a counterweight compartment as summarized above positioned between the pair of spaced supports, and is configured to receive and retain either the first or the second counterweight therein. Again, other details of this aspect of the invention are generally as set forth above.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.